Calaxin is an opisthokont-specific Ca
sensor. (A) A phylogenetic tree of Ca2+-binding proteins in the ascidian Ciona intestinalis. Proteins were aligned by CLUSTALW, and the tree was constructed by MEGA5. Ciona parvalbumin-like protein (XP_002129217) was used as the outgroup. The value shown on each branch represents the number of times that a node was supported in 1,000 bootstrap pseudo-replications. Accession numbers or NCBI reference sequence numbers of the sequence resources are as follows: calmodulin (AB076905), calaxin (AB079059), centrin (XP_004227465), troponin C (XP_002129347), NCS-1 (XP_002126443), hippocalcin (XP_002124848), KChIP (XP_004226075), calcineurin B subunit (CNB) (XP_002130765). (B) Multiple alignment of calaxin in opisthokont species. Asterisks, colons, or dots indicate identical residues in all sequences in the alignment, conserved substitutions, or semi-conserved substitutions, respectively. The amino acid residues identical to Ciona calaxin or to calaxin in other organisms are in red or blue, respectively. The sources of amino acid sequences are as follows: human calaxin (NP_078869), mouse calaxin (NP_080045), Ciona calaxin (AB079059), oyster calaxin (EKC38288), sponge calaxin (XP_003383675), and chytrid fungus calaxin (XP_006677085).